• Jonathon Jongsma's avatar
    drm/qxl: validate monitors config modes · bd3e1c7c
    Jonathon Jongsma authored
    Due to some recent changes in
    drm_helper_probe_single_connector_modes_merge_bits(), old custom modes
    were not being pruned properly. In current kernels,
    drm_mode_validate_basic() is called to sanity-check each mode in the
    list. If the sanity-check passes, the mode's status gets set to to
    MODE_OK. In older kernels this check was not done, so old custom modes
    would still have a status of MODE_UNVERIFIED at this point, and would
    therefore be pruned later in the function.
    
    As a result of this new behavior, the list of modes for a device always
    includes every custom mode ever configured for the device, with the
    largest one listed first. Since desktop environments usually choose the
    first preferred mode when a hotplug event is emitted, this had the
    result of making it very difficult for the user to reduce the size of
    the display.
    
    The qxl driver did implement the mode_valid connector function, but it
    was empty. In order to restore the old behavior where old custom modes
    are pruned, we implement a proper mode_valid function for the qxl
    driver. This function now checks each mode against the last configured
    custom mode and the list of standard modes. If the mode doesn't match
    any of these, its status is set to MODE_BAD so that it will be pruned as
    expected.
    Signed-off-by: default avatarJonathon Jongsma <jjongsma@redhat.com>
    Cc: stable@vger.kernel.org
    Signed-off-by: default avatarDave Airlie <airlied@redhat.com>
    bd3e1c7c
qxl_display.c 29.5 KB